1992年永胜5.4、5.1级地震异常及特征

ANOMALIES AND FEATURES OF THE 1992 YONGSHENG EARTHQUAKES (Ms5. 1, 5. 2)

对1992年12月云南永胜5．4、5．1级地震前的地震活动时空分布、某些前兆异常过程进行了分析讨论，并发现有3个较为明显的特征：①震前4个半月在滇西北地区（25°～28°，λE90°～101．5°）快速形成1条北东向地震条带（ML≥3．0级），②在孕震区范围内出现的前兆种类少、持续时间短、空间较分散；③永胜地震前滇西北地区的地震活动表现出显著的平静一密集一发震的特征。

Based on the analyses of the time-space distribution of the seismicity and the anomalouscourse, it is found to have 3 obvious features. The first feature, a seismic belt(ML≥3. 0) inNE direction formed in westnorthern Yunnan (25°~ 28°, 99°~101. 5°)during four and ahalf monthes before the earthquakes. the second one, the kinds of the precursor in seismogenic zone were fewer, the durations were shorter, and the precursors were more scatteredin space ； the third, the seismicity feature, calm-denseness-occurrence, was shown outstandingly before the events.Descriptors :Yunnan Seismic activity; Earthquake precursor; Anomaly Earthquakecorrelation method ;Earthquake prediction